Central retinal vein occlusion in a patient after being commenced on sildenafil citrate for pulmonary arterial hypertension.

A 75-year-old female was commenced on sildenafil for the treatment of pulmonary arterial hypertension (PAH) secondary to chronic obstructive pulmonary disease (COPD). She reported blurring of vision within 72 hours after starting treatment and was found to have a central retinal vein occlusion (CRVO). Such an occurrence is the second case reported to date, and we review the possible mechanisms and literature on the subject.

Sildenafil in treatment of pulmonary hypertension in the pediatric age group: an Egyptian experience

Pulmonary hypertension [PH] in children is defined as a mean pulmonary artery pressure >/= 25mmHg at rest or >/= 30 mmHg during exercise. Until last decade the diagnosis of primary PH [PPH] was a sentence of death. Sildenafil which is originally FDA approved for erectile dysfunction, has the ability to lower the pulmonary vascular pressure by inhibiting phosphodiesterase enzyme found richly in pulmonary vasculature and is tried nowadays in treating PH. Although Sildenafil use for PH in adults was recently approved by FDA, the data in pediatric population are scarce .This study aims at evaluating the use of Sildenafil in treating pediatric patients with PH. Twelve pediatric patients between January 2006 and January 2007 were Included in this study. Inclusion criteria were the presence of pulmonary hypertension diagnosed by transthoiracic echo. Patients were treated with oral Sildenafil [dose started at 0.1 mg/kg/dose every 6 to 8 hours and increased to 0.5 mg/kg/dose in children and up to 50 mg every 8 hours in adolescents]. Assessments of efficacy in terms of clinical improvement and/or decrease in pulmonary artery pressure by echocardiography were used as end points. Follow up was between 2 weeks and 7 months. Twelve patients presented with pulmonary hypertension with a mean age 7.7 years [range 0.3-15]. Five with primary pulmonary hypertension 1 with unoperated total anomalous pulmonary venous return [TAPVR], 5 postoperative complex cyanotic CHD and 1 with PH secondary to rheumatoid arthritis and lung fibrosis. After oral Sildenafil administration, there was an improvement in symptoms in 11/12 patients. Right ventricular pressure [RVP] decreased from a mean of 75 mmHg [range 61-118 mmHg] to a mean of 52.7 mmHg [range 35-90 mmHg] [p < 0.005].Mean RVP to mean Systolic Systemic Pressure [SSP] improved from 0.8:1 [range 0.5 to 0.1] to a mean of 0.5:1 [range 0.3-0.8], [p 0.004].Percentage of oxygen saturation increased from a mean of 77% [range 58-97%] to a mean of 88% [range 70-98%] [p 0.009]. Sildenafil is well tolerated in its oral form and appears to improve both pulmonary hemodynamics and the clinical status of pediatric patients with pulmonary hypertension as early as 2 weeks of therapy

Gene therapy and erectile dysfunction: the current status / 亚洲男科学杂志(英文版)

Current available treatment options for erectile dysfunction (ED) are effective but not without failure and/or side effects. Although the development of phosphodiesterase type 5 (PDE5) inhibitors (i.e. sildenafil, tadalafil and vardenafil) has revolutionized the treatment of ED, these oral medications require on-demand access and are not as effective in treating ED related to diabetic, post-prostatectomy and severe veno-occlusive disease states. Improvement in the treatment of ED is dependent on understanding the regulation of human corporal smooth muscle tone and on the identification of relevant molecular targets. Future ED therapies might consider the application of molecular technologies such as gene therapy. As a potential therapeutic tool, gene therapy might provide an effective and specific means for altering intracavernous pressure "on demand" without affecting resting penile function. However, the safety of gene therapy remains a major hurdle to overcome before being accepted as a mainstream treatment for ED. Gene therapy aims to cure the underlying conditions in ED, including fibrosis. Furthermore, gene therapy might help prolong the efficacy of the PDE5 inhibitors by improving penile nitric oxide bioactivity. It is feasible to apply gene therapy to the penis because of its location and accessibility, low penile circulatory flow in the flaccid state and the presence of endothelial lined (lacunar) spaces. This review provides a brief insight of the current role of gene therapy in the management of ED.

Evaluation and diagnostic testing of erectile dysfunction in the era of phosphodiesterase type 5 inhibitors / 亚洲男科学杂志(英文版)

The diagnosis and treatment of erectile dysfunction has changed dramatically since the availability of safe and effective oral therapies. Unfortunately, not all men can be adequately treated in this way, and might require more invasive testing to diagnose and treat the specific cause of their dysfunction. This review looks at the tests and strategies available for men who cannot be treated by oral therapy alone.

Tadalafil para o tratamento da hipertensão arterial pulmonar idiopática / Tadalafil as treatment for idiopathic pulmonary arterial hypertension

O uso de inibidores de fosfodiesterase, mais especificamente o sildenafil, no tratamento da hipertensão arterial pulmonar mostrou bons resultados, indicados por melhora dos parâmetros hemodinâmicos e da capacidade funcional. Poucos estudos existem a respeito dos efeitos de seus análogos como o tadalafil. O presente caso refere-se a uma paciente com hipertensão arterial pulmonar idiopática em classe funcional IV (NYHA) com resposta significativa ao uso de tadalafil.

Phosphodiesterase inhibitors like sildenafil have already been shown to improve functional capacity and hemodynamics in the treatment of pulmonary arterial hypertension. Few studies address the effects of new phosphodiesterase inhibitors as tadalafil. We report a case of a patient with idiopathic pulmonary arterial hypertension in functional class IV (New York Heart Association) with significant response to treatment with tadalafil.

Phosphodiesterase type 5 siRNA increases cGMP in the smooth muscle cells of human corpus cavernosum / 中华男科学杂志

<p><b>OBJECTIVE</b>To investigate the effect of phosphodiesterase type 5 (PDE5) small interfering RNA (siRNA) on the cGMP in the smooth muscle cells of human corpus cavernosum, and to provide an experimental groundwork for the gene therapy of erectile dysfunction (ED).</p><p><b>METHODS</b>Small interfering RNAs targeting PDE5 gene were synthesized by using web design software provided by Ambion, three siRNAs and a control siRNA were synthesized by Ambion. siRNAs were transfected into the smooth muscle cells of human corpus cavernosum by using siPORT Lipid reagent. cGMP was detected by ELISA at different times (24, 48, 72 and 96 h) after transfection.</p><p><b>RESULTS</b>The cGMP levels of the siRNA1, siRNA2 and siRNA3 groups were significantly higher than those of the siRNA control and blank control groups (P < 0.05), and so was it in the siRNA1 group than the siRNA2 and siRNA3 groups (P < 0.05), with significant difference between the siRNA control and the blank control group (P > 0.05).</p><p><b>CONCLUSION</b>The synthesized siRNAs in vitro are capable of increasing the level of cGMP in the smooth muscle cells of human corpus cavernosum, different siRNAs with different capabilities. The siRNA technique could provide not only an extremely powerful tool for the functional analysis of genome but also a new approach to ED gene therapy.</p>

Recent insights into androgen action on the anatomical and physiological substrate of penile erection / 亚洲男科学杂志(英文版)

Erectile response is centrally and peripherally regulated by androgens. The original insights into the mechanisms of action of androgens were that androgens particularly exert effects on libido and that erections in response to erotic stimuli were relatively androgen-independent. It was shown that sexual functions in men required androgen levels at the low end of reference values of testosterone. So it seemed that testosterone was not useful treatment for men with erectile difficulties, particularly following the advent of the phosphodiesterase type 5 (PDE5) inhibitors. However, approximately 50% of those treated with PDE5 inhibitors discontinue their treatment. A number of recent developments shed new light on testosterone treatment of erectile dysfunction (ED) in aging men. (1) A recent insight is that, in contrast to younger men, elderly men might require higher levels of testosterone for normal sexual functioning. (2) Several studies have indicated that PDE5 inhibitors are not always sufficient to restore erectile potency in men, and that testosterone improves the therapeutical response to PDE5 inhibitors considerably. (3) There is growing insight that testosterone has profound effects on tissues of the penis involved in the mechanism of erection and that testosterone deficiency impairs the anatomical and physiological substrate of erectile capacity, reversible upon androgen replacement. The synthesis of PDE5 is upregulated by androgens, and the arterial inflow into the penis is improved by giving androgen. The above invites a re-examination of the merits of giving testosterone to aging men with ED. The beneficial effects of PDE5 inhibitors may only be optimally expressed in a eugonadal environment.

Construction of an antisense RNA recombinant adenovirus vector of the human PDE5A1 gene promoter / 中华男科学杂志

<p><b>OBJECTIVE</b>To construct an antisense RNA recombinant adenovirus vector of the human PDE5A1 promoter gene.</p><p><b>METHODS</b>A cDNA fragment containing the human PDE5A1 promoter and the human PDE5A1-specific exon was determined according to the gene bank. The antisense RNA fragment was synthesized artificially and subcloned into the pENTR. Then, the sequence of pENTR fragment was detected, and the recombinant adenovirus vector pAd/CMV/V5/antisense-PDE5A1 was constructed by LR reaction with the Gateway expression system. The identified recombinant adenovirus plasmid was digested with Pac I and transformed into 293A cells to package recombinant adenovirus particles. The recombinant adenovirus particles were tested with PCR technique and purified after acquisition by CsCl density gradient ultracentrifugation.</p><p><b>RESULTS</b>The sequencing result showed a 145 bp fragment in pENTR, which was proved to be the domain of the antisense RNA fragment. PCR confirmed that the antisense RNA fragment was cloned into the recombinant adenovirus vector pAd/CMV/V5/antisense-PDE5A1 successfully and could infect 293A cells. The titer of virus stocks was up to 10(8) - 10(10)/microl after purification.</p><p><b>CONCLUSION</b>With the Gateway expression system, the culturing and reproduction of 293A cells can reproduce recombinant adenovirus pAd/CMV/V5-DEST successfully, and the recombinant adenovirus vector can meet the need of in vivo gene transfection in laboratory studies.</p>

Effects of icariin on erectile function and expression of nitric oxide synthase isoforms in castrated rats / 亚洲男科学杂志(英文版)

<p><b>AIM</b>To investigate the effect of icariin on erectile function and the expression of nitric oxide synthase (NOS) isoforms in castrated rats.</p><p><b>METHODS</b>Thirty-two adult male Wistar rats were randomly divided into one sham-operated group (A) and three castrated groups (B, C and D). One week after surgery, rats were treated with normal saline (groups A and B) or oral icariin (1 mg/[kg.day] for group C and 5 mg/[kg.day] for group D) for 4 weeks. One week after treatment, the erectile function of the rats was assessed by measuring intracavernosal pressure (ICP) during electrostimulation of the cavernosal nerve. The serum testosterone (ST) levels, the percent of smooth muscle (PSM) in trabecular tissue, and the expression of mRNA and proteins of neuronal nitric oxide synthase (nNOS), inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS) and phosphodiesterase V (PDE5) in corpus cavernosum (CC) were also evaluated.</p><p><b>RESULTS</b>ICP, PSM, ST and the expression of nNOS, iNOS, eNOS and PDE5 were significantly decreased in group B compared with those in group A (P 0.01). However, ICP, PSM and the expression of nNOS and iNOS were increased in groups C and D compared with those in group B (P 0.05). Changes in ST and the expression of eNOS and PDE5 were not significant (P 0.05) in groups C and D compared with those in group B.</p><p><b>CONCLUSION</b>Oral treatment with icariin ( 98.6 % purity) for 4 weeks potentially improves erectile function. This effect is correlated with an increase in PSM and the expression of certain NOS in the CC of castrated rats. These results suggest that icariin may have a therapeutic effect on erectile dysfunction.</p>

Cholinergic-NO-cGMP mediation of sildenafil-induced antinociception.

Acetylcholine and cholinomimetic agents with predominant muscarinic action are known to increase the concentration of cGMP by activation of nitric oxide signaling pathway in the nociceptive conditions. The present study was aimed to investigate the NO-cGMP-PDE5 pathway in nociceptive conditions in the experimental animals. Nociceptive threshold was assessed by acetic acid-induced writhing assay (chemonociception) or carrageenan-induced hyperalgesia. Sildenafil [1-5 mg/kg, ip, 50-200 microg/paw, intraplantar (ipl)] produced dose dependent antinociception in both the tested models. Coadministration of acetylcholine (50 mcg/paw, ipl) or cholinomimetic agent, neostigmine (0.1 mcg/kg, ip and 25 ng/paw, ipl) augmented the peripheral antinociceptive effect of sildenafil. This effect was sensitive to blockade by L-NAME (20 mg/kg, ip, 100 microg/paw, ipl), a non-selective NOS inhibitor and methylene blue (1 mg/kg, ip), a guanylate cyclase inhibitor, which per se had little or no effect in both the models of nociception. Further, the per se analgesic effect of acetylcholine and neostigmine was blocked by both L-NAME and methylene blue in the models of nociception, suggesting the activation of NO-cGMP pathway. Also, both L-NAME and methylene blue blocked the per se analgesic effect of sildenafil. These results indicate the peripheral accumulation of cGMP may be responsible for antinociceptive effect, and a possible interaction between cholinergic agents and PDE5 system in models of nociception.

Effect of DA-8159, a Selective Phosphodiesterase Type 5 Inhibitor, on Electroretinogram and Retinal Histology in Rabbits

DA-8159, a selective inhibitor of phosphodiesterase type 5, was developed as a new drug for erectile dysfunction. The effect of DA-8159 on the electroretinogram (ERG) and the retinal histopathology were evaluated in rabbits. The ERG was performed prior to, and 1 and 5 hr after DA-8159 (5 to 30 mg/kg) administration. The plasma concentration of DA-8159 was determined at each time point, and retinal microscopic examination was also performed. There was no statistically significant ERG change at any dose or at any time. Though the 30 Hz flicker showed a prolongation of the implicit time at 5 hr after the administration of either DA-8159 15 mg or 30 mg/kg (p<0.05), but concurrent amplitude decreases were not statistically significant. At a dose of 5 mg/kg, no test drug was detected in the blood after either 1 or 5 hr. At either 15 mg/kg or 30 mg/kg, there was a dose-dependent increase in the blood concentration after 1 hr of drug administration, which decreased with time. In light and electron microscopic examinations of the retina, there was no remarkable change at any dose. These results suggest DA-8159 has a low risk potential to the retina, but further evaluation on the visual functions in human is needed.

Experimental research of PDE5 activity in corpora cavernosa of ganyu qizhi rat model / 中华男科学杂志

<p><b>OBJECTIVES</b>To study the PDE5 activity in corpora cavernosa of the Ganyu Qizhi model penis and the effect of the Chinese herbal medicine Shugan Liqi Huoxue (SLH) ointment on it.</p><p><b>METHODS</b>Non-injury stress stimulus method similar to human spirit stress was used to extablish the Ganyu Qizhi animal(rat) model, and the PDE5 activity in corpora cavernosa of the rat penis was measured by the method of immunohistochemistry and computer image analysis.</p><p><b>RESULTS</b>The PDE5 activity in corpora cavernosa of the high-dosage SLH group was significantly different from that of the model group (P < 0.01).</p><p><b>CONCLUSION</b>Ganyu Qizhi may increase the PDE5 activity in corpora cavernosa of the penis while SLH can reduce such activity.</p>

Comparison of efficacy and safety of phosphodiesterase type 5 inhibitors in the treatment of erectile dysfunction / 中华男科学杂志

Since the introduction of the phosphodiesterase type 5 (PDE-5) inhibitor sildenafil in 1998, there has been a fundamental change in the treatment of erectile dysfunction (ED). Sildenafil has already been used by over 20 million men in over 100 countries, with a death rate similar to that of general population. The success rate of sildenafil amounts to an average of over 80%, and sildenafil has become the first choice for patients with ED. The development of two new PDE-5 inhibitors, vardenafil and tadalafil, has added to the options for the treatment of ED. In this review, a comparison is made of the pharmcodynamics, pharmacokinetics and adverse reactions between the three PDE-5 inhibitors to assess their efficacy and safety.

Effect of berberine on the mRNA expression of phosphodiesterase type 5 (PDE5) in rat corpus cavernosum / 中华男科学杂志

<p><b>OBJECTIVE</b>To further investigate the action mechanisms of berberine (Ber) and to assess the effects of Ber on the mRNA expression of phosphodiesterase type 5 (PDE5) in rat corpus cavernosum.</p><p><b>METHODS</b>After incubating with Ber for 1 or 3 h respectively, we examined the levels of PDE5 mRNA by reverse transcription polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>There were PDE5A1 and PDE5A2 mRNA expressions in the rat corpus cavernosum with PDE5A2 as the dominant isoform. Ber could obviously inhibit the mRNA expression of the two isoforms in the rat penis and bring on a pronounced decrease in PDE5A2 (P < 0.01).</p><p><b>CONCLUSION</b>The present study indicates that the inhibitory effect of Ber on PDE5 mRNA expression, especially on PDE5A2, might account for its molecular mechanism for treating ED.</p>

The efficacy and tolerability of sildenafil in patients with moderate-to-severe pulmonary hypertension.

BACKGROUND: Pulmonary arterial hypertension is a life-threatening disease for which continuous intravenous infusion of prostacyclin has proved effective. However, it carries the risk of serious complications arising from the complex delivery system. Prostacyclin analogs, endothelin antagonists, and the phosphodiesterase-5 inhibitor sildenafil are emerging promising therapies. This study was aimed at evaluating the utility of oral sildenafil in patients with pulmonary hypertension of varied etiology, poorly controlled on conventional treatment. METHODS AND RESULTS: Ten consecutive patients with pulmonary hypertension, either primary or related to previous left-to-right shunts, thromboembolism, or interstitial lung disease, poorly controlled on conventional therapy such as warfarin, calcium antagonists, digitalis, and diuretics, were included. A thorough clinical, laboratory, and comprehensive echo Doppler evaluation was performed before enrollment in the trial to establish the diagnosis and obtain baseline data. Subjects received sildenafil 25 mg 8 hourly, or a matching placebo for two weeks each, in a randomized, double-blind, crossover design. A run-in period of two weeks was permitted between the two therapies during which patients continued to receive the conventional therapy without any vasodilator. At the end of each therapy period, the patients were evaluated for symptoms, New York Heart Association class, distance covered during the 6 min walk test, rating of modified Borg dyspnea score, and systolic pulmonary artery pressure using echo Doppler. The differences in the above variables at the end of sildenafil and placebo therapies were compared. Nine patients completed the study protocol. Sildenafil, compared to placebo, was associated with improved exercise tolerance as determined by the 6 min walk test (266.67+/-131.45 m v. 170+/-105 m; p<0.005), decrease in modified Borg dyspnea score (3.56+/-1.01 v. 5.11+/-1.45; p<0.01), decrease in Doppler-estimated pulmonary artery systolic pressures (55.33+/-16.52 mmHg v. 75.33+/-19.75 mmHg; p<0.005), improvement in New York Heart Association class (2 patients), and improvement in symptoms. Sildenafil was well tolerated with no untoward effects; further, no significant changes in heart rate or blood pressure occurred during the study period. CONCLUSIONS: Sildenafil improves exercise capacity and symptoms, and decreases pulmonary artery pressures in patients with primary or secondary pulmonary hypertension of varied etiology.

The effects of antisenes oligodeoxynucleotide on the cyclic nucleotide monophosphates in smooth muscle cells of human corpus cavernosum / 中华男科学杂志

<p><b>OBJECTIVES</b>To investigate the effects of antisense oligodeoxynucleotide(ASON) on the cyclic nucleotide monophosphates (cNMP) in smooth muscle cells of human corpus cavernosum, and provide experimental groundwork for the gene therapy of erectile dysfunction.</p><p><b>METHODS</b>PDE5 gene ASON(containing exon 1) was transfected into the corpus cavernosum smooth muscle cells with the presence of liposome DOTAP. Another sense oligodeoxynucleotide(SON) and 1% of bovine serum were also transducted into the cells as controls. Two of cNMP, cAMP and cGMP, were probed and measured by ELISA at 1, 2, 4, 6, 10, 24 and 48 h after transfection.</p><p><b>RESULTS</b>After transfection, the level of cGMP(1-6 h) in human corpus cavernosum smooth muscle cells was significantly higher than that in controls(P < 0.01).</p><p><b>CONCLUSIONS</b>The PDE5 gene ASON had been showed to manifest stimulative effect on the cGMP in smooth muscle cells of human corpus cavernosum in vitro, and it provides experimental groundwork for the gene therapy of erectile dysfunction.</p>

Equilibrium kinetics modal for the cGMP-stimulated phosphodiesterase of brain coated vesicles

An equilibrium kinetics model is proposed to described some of the enzymatic properties of the cyclic GMP-stimulated phosphodiesterase activity associated with brain clathrin coated vesicles. The model assumes the presence of pharmacologically distinct regultory and catalytic domains in the enzyme. The model contemplates that random fashion occupancy of the regulatory site by the substrate, cyclic GMP, induces a conformational change which leads to the generation of a actived catalytic state. Therefore, cyclic GMP is a positive allosteric modulator of the coated vesicle enzyme. Experimental data revealed that occupancy or activation of the regulatory site was not essential for catalysis to occur since hydrolysis occured after loss (200%) of the activation by cyclic GMP. This constitutes an example of non-essential substrate activation. Analysis of this PDE following activation by cGMP and after loss of the regulation, activation capacity of the enzyme allows the calculation of the various kinetic parameters inherent in the model